Abstract: An improved process of performing analysis methods based upon biospecific affinity reactions in heterogeneous systems, wherein a ligand dissolved in a liquid is reacted with a receptor immobilized on a carrier, characterized by utilizing as the carrier a porous matrix in the form of a material body having an open capillary pore system capable of absorbing and retaining liquid phase and having such limited void dimensions that the total reaction rate of the biospecific reaction or reactions within the pore system between ligand and immobilized receptor will be at least substantially independent of the diffusion of the ligand in the liquid phase. A porous matrix for use in said process has the characteristics mentioned above.

Abstract: There is described a method for splitting at least one disulphide bond --S--S--, where each of the sulphur atoms is directly bound covalently to its respective aliphatic carbon atom in an organic substance which contains at least one such disulphide bond, in which each bond --S--S-- which is split is converted substantially to two reactive groups of the formulae --S--S--R.sub.1 and R.sub.2 --S--S--, where R.sub.1 and R.sub.2 are equal or different and each is an organic residue. Splitting of the bond is effected by reacting said organic substance with a mixture of a compound R.sub.3 --S--S--R.sub.4 and a compound capable of existing in the tautomeric forms R.sub.5 --S--H and HR.sub.5 .dbd.S or corresponding resonance-stabilized anion forms, in which compounds the residues R.sub.3, R.sub.4 and R.sub.5 (i) are organic residues of which all are different, two are equal or all are equal, and (ii) are defined in (a) that each of the aforesaid sulphur atoms in the compounds R.sub.3 --S--S--R.sub. 4 and R.sub.

Abstract: In the formation of polymeric layers, especially anisotropic polymeric layers, on a solid substrate on which the layer is formed by cross-linking of an organic substance which can be cross-linked, the cross-linking is performed in a manner such that a concentration gradient of at least one of the components controlling the cross-linking reaction is formed in the boundary layer between the substrate to be coated and the surrounding solution, which concentration gradient is adjusted so that cross-linking can take place in the boundary layer but not in the surrounding solution. The concentration gradient is preferably achieved by impregnating the substrate with at least one of the components which control the cross-linking reaction and which tends to diffuse into the solution on contact therewith.